Fuel gauge literally burned

It would be to reduce to a smooth 6v, prior to the stock fuel gauge regulator. As I understand, the stock equipment is somewhat sensitive to input voltage. A more accurate reading could be had by what's being called a gauge regulator (vs. instrument voltage regulator). I picked the majority of this up from Vernco in Fuel Gauge 101.

 

Yes, I think you have a good idea there. I have been right on the edge of doing the same thing myself. I had a gauge set almost self destruct when the built in regulator apparently stuck at some high level. Both gauges just went to the peg while I was driving, I was almost home and got it parked before they smoked.

All it would take would be something like an LM 317 in the TO3 package, that package will dissapate 20W if it is on a heat sink. That would be more than enough, the regulator would have to reduce the 12V (actually as much as 14.2) down to about 5V. Figure it has to waste about 9V, even assuming 2A current that is still 18W. You would need a variable resistor for control, a little piece of aluminum for a heat sink. You can find a schematic online, or Howard or myself could draw one up.

The advantage of the regulator would be as you thought, adjusting the gauge accuracy. For instance, the temp gauge I am using now has a regulator in it that fluctuates between 3-6V causing the needles to continually move, and stay below what I think they should be reading. So the idea would be to use an electronic regulator to get the temp gauge to midrange with the electrical sending unit at a known temp of 180°. That is what I would consider a desirable operating temp, and I'd like my gauge to show midrange at that temp.

Don

 

This is what I ordered:
A 7806 6V regulator (which should handle high fluctuations), 2 10uF 25v radial capacitors (high temp variety), and an NTE 403 heat sink. All for less than 5 bucks.

I hope that this will add a safeguard to the gauges, or at the least, improve readings.

So I'm still just wondering about the extra protection of a fuse? Slow burn 2 amp? I'm guessing the fuel gauge wouldn't even draw an amp... I could do some testing, but the gauge is burnt up... and out of the module... and etc etc

 

Ok, I'll order some diodes from Jameco too. I'm actually getting enough of everything to make multiple samples, so that when I screw up the first 3 to 5 regulators, numbers 6 & 7 should get r done. Ha!

 

I've decided to give an update here. Finally have figured out the entire fuel gauge system, and calibrated the sender to the tank. With much thanks to Vernco site. I can't over-emphasize the importance of having a proper ground for both the sender, and gauge/cluster housing.

Notice how I soldered some conductive solder wick per Vern's instructions. Also laid a bead down around the main body of the sender, where it's riveted from two halves.

Here's the setup. Making sure everything works on the bench. Yup, Vernco.com on the laptop.


Anyways, all is well and things work properly now. Wanted to give the update and say thanks to everyone who ha helped out!

 

The old gauge is working "properly," however with it being in such an abused state, I opted to go with a new one. Thanks for all your help Howard!!!

 

So did you abandon your solid state voltage reducer (regulator) as don't see it in the pic? Was just curious how it worked?

 

So it actually worked very well on the bench, reducing 12.54v down to 6.09. I even drilled the instrument housing an installed the regulator nicely. But as luck would have it, I was dry-fitting the entire instrument cluster back to the "dash," with original wiring configuration, and of course, it worked well... and I was too tired and knuckle sore to pull it out again and re-wire to my new format.

Here's the way it looks.


I will (keep telling myself) pull it all out again and re-install with the voltage regulator hooked up. Probably when I burn up this fuel gauge. It's just such a pain to be cramming under the dash fumbling through wires and busting my knuckles.... you know?

 

You may want to order an in tank sender unit as well. These things usually go out in pairs. Losing ground can cause the fuel sender, fuel gauge, and temp sender to go north.

Don't try to test the new gauge outside of the cluster or you may end up buying yet another gauge or sender unit.

 

I have a fuel gauge with a bad internal regulator. So this external regulator you built by-passes the internal regulator or do you use it in series with the internal regulator?

 

Would have been in place of the stock regulator. It works differently, although similar to, the original. The original has a resistor type regulator that would work well with a constant input voltage, but we all know these Jeeps are capable of wild fluctuations. My CJ5 until very recently would have dimming/brightening headlights and a jumping Voltmeter when just idling. Now, if I understand correctly, you can place one of these home-made voltage regulators in series with a 6v system's gauge, which may work very well indeed.

Has anyone tried one of these regulators in series with a 12v system? It may actually work perfectly.

 

I gave my CJ5 to the specialist to repair the gearbox, change shock absorbers and - fix correctly the fuel gauge.

They charge me for this of course, and it is quite expensive but I am not able to do it, I have to work and I want this to be done.

All is done except the fuel gauge. They bought a new tank gauge, check the wires, and no success.

It was the same with me. They are not specailistes of electricity and resistance ohm problems, they use to make new Willys WWII for collectors.

SO I said : leave it to me!

I'll take time to check all and maybe modify the dashboard, to make it open on hinges on the center parts.

I have some difficulties to work on it from behind, I use a mirror.

I would like to go on the seaside with my Jeep, like a did 35 years ago in south of France.

So I need a gauge working. I changed all once, I have to check all now and start from 0.

Some people are experts in electricity, and they have the tools. TO get resistors (adaptating) is complex, and move the dash unpleasant.

The idea, as some did, to make a special dash is very good. To have a Jeep means take time to work. I bought it in 2011, it will be OK in 2014.

And some money invested.

 

I am so confused, I know nothing, got lost along time ago on this one. Hope my gauge never quits working. Too deep for me.